Index mechanism for rotary switches



Nov. 25, 1969 D. .1. KLEIN INDE-X MECHANISM FOR. ROTARY SWITCHES 2 Sheets-Sheet 1 Filed Oct. 16, 1967 INVENTOR DIETRICH J. KLEIN ATTORNEYS Nov. 25, 1969 D. J. KLEIN 3,480,748

INDEX MECHANISM FOR ROTARY SWITCHES Filed Oct. 15, 1967 ZSheetS-Sheet 2 INVENTOR DIETRICH J. KLEIN BY 1, M, k .1 M

ATTORNEYS United States Patent O 3,480,748 INDEX MECHANISM FOR ROTARY SWITCHES Dietrich J. Klein, Ormond Beach, Fla., assignor, by mesne assignments, to Electro-Tec Corporation, a corporation of Delaware Filed Oct. 16, 1967, Ser. No. 675,398 Int. Cl. H01h 19/32; Gg 5/06 US. Cl. 200-66 9 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention relates to a rotary electric switch, and more particularly to such a switch in which the contact brush moves from contact terminal to contact terminal with a snap action.

Description of the prior art Various types of rotary snap action switches are known. These switches commonly comprise a set of rotary contact brushes which are resiliently connected to an actua tor shaft by a spring. The rotary contacts are held in electrically conductive positions with respect to a plurality of circumferentially spaced contact terminals by detent means. As the actuator shaft is turned, the detent means holds the rotary contacts until sufiicient energy has been stored in the Spring to overcome the retaining force. Additional rotation of the actuator shaft causes the detent means to slip and the rotary contacts to snap into the next detent recess aligned with the succeeding stationary contact terminal. In such switches there is no positive connection between the actuator shaft and the rotary contacts other than through the spring. Thus, it is possible for the contacts to overshoot their intended positions once they have overcome the restraining force of the detent means; Further, since the actuator shaft is always connected to the rotary contacts by a spring, the rotary contacts must be constructed to withstand the full force applied to that spring by the actuator shaft prior to the slipping of the detent means. Such construction adds weight to the rotary member and therefore increases the momentum of the member and the likelihood that it will overshoot its desired position.

SUMMARY OF THE INVENTION The rotary switch of the present invention eliminates the above-mentioned deficiencies in the previously known switches by completely disengaging the actuator shaft from the rotary contacts during the initial switching movement of the actuator shaft. After the actuator shaft has been turned more than half of its travel to the next position, it is once again connected to the rotary contacts, which are at that time out of alignment with the actuator shaft. By the time the actuator shaft reaches the desired position, the rotary contacts have caught up 3,480,748 Patented Nov. 25, 1969 with it and are then rigidly held in alignment therewith. Therefore, the rotary contacts remain. stationary during more than half of the period required for turning the actuator shaft from One position to the next succeeding position. Since the time required for the actual switching process of the rotary contacts is substantially less than required to reposition the actuator shaft, arcing conditions are minimized, thereby greatly prolonging the life of the contacts. An additional advantage to the present invention lies in the fact that it is very difficult, if not impossible to hold the contacts in an arcing position for any extended length of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front view of the index mechanism for rotary switches embodying the improvements of the present invention;

FIGURE 2 is a sectional view of the index mechanism of FIGURE 1 taken along line 2-2 of FIGURE 1;

FIGURE 3 is a sectional view of the index mechanism of FIGURE 1 taken along line 3-3 of FIGURE 1;

FIGURE 4 is a front view of the index mechanism shown in FIGURE 1, but showing the detent plates completely disengaged from the actuator fork;

FIGURE 5 is a front view of the index mechanism of FIGURE 1, but showing the detent plates as they initially re-engage the actuator fork;

FIGURE 6 is a front view of the index mechanism of FIGURE 1, but showing the rotatable contact as it breaks with the fixed contact;

FIGURE 7 is a front view of the index mechanism of FIGURE 1, but showing the rotatable contact as it makes with the next succeeding fixed contact; and

FIGURE 8 is a front view of the index mechanism of FIGURE 1 after the switching operation has been completed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURES 1 and 2, the index mechanism of the present invention is provided with an actuator fork 10 which is rigidly connected to a contact drum, not shown, having a number of contact brushes 12 of which only one has been shown. Each of the contact brushes 12 makes contact with one of a number of sta tionary, circularly arranged contact terminals 14, 16, 18 and 20 in a contact deck assembly. Only one set of contact terminals has been shown for illustration purposes. However, it will readily be understood that for each contact brush there is a corresponding set of contact terminals. As is conventional, for each row of contact terminals, there is one wiper terminal slightly offset from the plane of the corresponding contact brush, and there is a slip ring combination and an internal connection between the slip ring and the contact brushes to complete a circuit between the Wiper terminals and any one of the contact terminals depending on the position of actuator fork 10.

An actuator assembly comprises a pair of detent plates 22 and 24 positioned one in front of the other. Each plate has a cross-shaped opening therein. The horizontal portions 23 of the openings are larger than the portion of actuator fork 10 which extends therethrough. A spring 26 is arranged in tension in the vertical portion 25 of the openings between the detent plates. Spring 26 resiliently urges plate 22 downwardly as shown in FIGURE 2 and urges plate 24 upwardly to extended positions as shown in that figure. It will be understood by those skilled in the art that the spring can be arranged in any convenient manner without affecting the operation of the device.

Detent plates 22 and 24 are mounted for radial sliding movement relative to each other, but are restricted by lips 27 and 28 of actuator 21, only partially shown, from relative rotational movement. The function of actuator 21 and lips 27 and 28 is better understood by reference to FIGURE 3.

The bottom edge 29 of horizontal portion 23 of the opening in detent plate 22 cooperates with the flat, bottom side 30 of actuator fork 10 under action of spring 26 to align the actuator fork with the detent plate. In like manner, the top edge 32 of horizontal portion 23 of the opening in detent plate 24 cooperates with the top flat surface 34 of the actuator fork for the same purpose. Thus, when the detent plates are in the position shown in FIGURE 2, the actuator fork 10 and the contact brush 12 carried thereby is aligned with the detent plates.

There is provided means, represented generally by reference numeral 35, for effecting disengagement of actuator assembly 21 from actuator fork 10 during part of the switching operation. Detent plates 22 and 24 are carried in a stationary index housing 37, only partially shown. The inside surface of the index housing has a series of circumferentially spaced apart scallops 36 located on radii which lie between contact terminals 14, 16, 18, 20, etc. Rollers 38 and 40 carried in suitable grooves in the ends of detent plates 22 and 24, respectively, cooperate with the scallops 36 and the recesses 39 therebetween to provide a detent function, the recesses defining a first set of fixed positions for detent plates 22 and 24 corresponding to the circumferential spacing of contact terminals 14, 16, 18 and 20. Additionally, as detent plates 22 and 24 are rorated from the position shown in FIGURE 2, rollers 38 and 40 ride up the sides of scallops 36 to force the detent plates radially inwardly against the force of spring 26 to their contracted positions.

OPERATION FIGURE 2 shows the index mechanism in its rest configuration with detent plates 22 and 24 in their fully extended positions. Contact brush 12 is aligned with contact terminal 16, and actuator fork 10 is tightly engaged by the respective edges 29 and 32 of the horizontal portion 23 of the openings in detent plates 22 and 24 under the action of spring 26. In this position, rollers 38 and 40 are located in recesses 39 between pairs of scallops 36.

As actuator shaft 41 is rotated, detent plates 22 and 24 revolve toward the positions shown in FIGURE 4. Of course, it is understood that the actuator shaft may be rotated in the opposite direction, in which case the following explanation of events occurs in a counterclockwise instead of a clockwise direction.

As the detent plates rotate toward the fully contracted position shown in FIGURE 4, they will be forced radially inwardly by the coaction between rollers 38 and 40 and scallops 36. In moving inwardly, the detent plates are disengaged from actuator fork 10. Therefore, the actuator fork 10 and contact brush 12 remain in their original positions, held there by the fricton between brush 12 and contact terminal 16. FIGURE 4 shows the assembly at an intermediate stage in which rollers 38 and 40 have reached the high points of scallops 36.

FIGURE shows the assembly in a position in which rollers 38 and 40 have just passed the high points on scallops 36 and are continuing down the back sides thereof. This stage in the progression of actuator assembly 21 defines a second set of positions spaced 'between the first set of fixed positions at which movement of actuator shaft will begin. Detent plates 22 and 24 are now moving radially outwardly under the action of spring 26, and the rollers are moving into the next set of recesses 39. Edges 29 and 32 have just come into contact with actuator fork 10, but have not yet started to rotate it.

As the actuator plates progress from the position shown in FIGURE 5 to that shown in FIGURE 6, actuator fork 10 starts a rapid movement under the force of spring 26 due to the diminishing space between edges 29 and 32. Upon reaching the position shown in FIGURE 6, contact brush 12 is just ready to break with contact terminal 16. Moving rapidly under the influence of spring 26, the actuator fork and the contact brush carried thereby snaps over toward contact terminal 18. FIGURE 7 shows the relative positions of the elements as contact brush 12 just makes with contact terminal 18. Completing the switching operation, contact brush 12 and actuator fork 10 move into alignment with detent plates 22 and 24 as the index mechanism reaches the position shown in FIGURE 8. This position, like that of FIGURE 2, is stable.

It can readily be seen from the above description that the period of time required for the contact brush to move from the break position shown in FIGURE 6 to the make position shown in FIGURE 7 is substantially less than that time required for the movement detent plate assembly to move from the rest position of FIGURE 1 to the rest position of FIGURE 8. Threfore, the actual switching process is greatly accelerated, and arcing conditions are thereby minimized. Varying the dimensions of the aforementioned components would result in the availability of a multitude of timing and torque combinations to satisfy any desired design requirements.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An index mechanism for use in conjunction with a switch having at least one rotary contact brush and a plurality of circumferentially spaced, stationary contact terminals, said index mechanism comprising:

(a) an actuator fork operably connected to said rotary contact 'brush;

(b) an actuator assembly including means selectively engageable with said actuator fork for aligning said contact brush with said actuator assembly, said assembly rotatable between any two of a first set of fixed positions corresponding to the circumferential spacing of said contact terminals and having a second set of positions spaced between said first set of fixed positions; and

(0) means for effecting disengagement of said actuator assembly from said actuation fork during rotation of that assembly from said first set of positions and for effecting re-engagement of said actuator assembly with said actuator fork after that assembly has passed the next succeeding one of said second set of positions, whereby said contact brush will remain stationary during movement of said actuator assembly from said first set of positions to said second set of positions and will be snapped into alignment with said actuator assembly during movement of that assembly from said one of said second set of positions to the next succeeding fixed position of the first set.

2. An index mechanism as defined in claim 1 wherein said actuator assembly includes plates moveable in first and second opposite directions to alternately engage and disengage said actuator fork, the movement of said plates being controlled by said last mentioned means.

3. An index mechanism as defined in claim 1 wherein said last mentioned means includes:

(a) an index housing having circumferentially spaced recesses corresponding to said stationary contact terminals; and

(b) detent means carried by said actuator assembly for cooperation with said index housing, said detent means being positioned in said recesses when said actuator assembly is in one of said first set of positions.

4. An index mechanism as defined in claim 3 wherein said actuator assembly includes plates moveable in first and second opposite directions by said detent means to alternately engage and disengage said actuator fork.

5. An index mechanism as defined in claim 1 wherein:

(a) said actuator fork is a rotatable shaft having a pair of fiat surfaces spaced on opposite sides of its axis of rotation;

(b) said actuator assembly includes first and second plates, each having extended positions and a control surface thereon for engagement with opposite ones of said flat surfaces of said actuator fork when said plates are in their extended positions, said plates being moveable in opposite directions to contracted positions to disengage said control surfaces from said fiat surfaces; and

(c) said last mentioned means includes resilient means for biasing said plates away from their contacted positions, and separate means for overcoming said biasing means.

6. An index mechanism as defined in claim 5 wherein said separate means includes:

(a) an index housing having circumferentially spaced scallops spaced between recesses which correspond to said stationary contact terminals, said recesses and scallops lying in the planeof rotation of said plates;

(b) detent means carried by said plates for cooperation with said index housing whereby said plates will be in their extended positions when said detent means are located in said recesses and in their contracted positions when said detent means are located on said scallops.

7. An index mechanism as defined in claim 5 wherein said control surfaces are sides of openings in said plates through which said actuator fork extends.

8. An index mechanism as defined in claim 5 wherein said plates are constrained to rotational movement about said axis of rotation of said actuator fork and radial movement along a line through said axis, only.

9. An index mechanism as defined in claim 5 wherein said resilient means comprises a spring connected between said first and second plates.

References Cited UNITED STATES PATENTS 7/1954 Willyard 74-527 4/1958 Bauer 74-527 US. Cl. X.R. 74-527 

